I propose to test and extend a theory of individual differences in effeicient cognitive performance. This theory specifies how the personality dimensions of impulsivity, achievement motiviation, and anxiety relate to the motivational constructs of effort and arousal. Furthermore, the theory specifies how effort and arousal affect two components of information processing, attention and memory functioning. Finally, the theory predicts how attention and memory functioning affect performance on complex tasks such as the Scholastic Aptitude Test of the Graduate Record Examination. I am proposing four different approaches to test this theory: 1: psychometric investigations of the adequacy of scales which measure the personality traits; 2. univariate studies which will examine how each personality dimension interacts with particular situational moderators such as success or failure feeback, time of day, or caffeine; 3. analyses of the effect of manipulations of arousal and effort on information processing tasks; and 4. multivariate analyses which will test the theory of individual differences and performance as a whole.